Exposures to bioaerosols in the workplace have become a significant issue in recent years. It is essential to be able to accurately assess these potential health risks. Furthermore, because each person will react differently, it is necessary to perform such assessments on an individual basis. Workplace bioaerosols include bacteria, fungi, viruses, microbial toxins and various allergens. Numerous devices exist that are capable of collecting bioaerosols, but many are not designed for personal use. Additionally, the majority of existing devices confer a high degree of biological stress resulting in a significant loss in viability. Preservation of viability is crucial for accurate exposure assessments in that viable microorganisms pose a greater health risk. This proposal has four objectives: (1) to design and construct a personal bioaerosol sampler incorporating a re-circulating liquid cyclone collection medium, (2) to test the sampling efficiency of the proposed personal sampler in an aerosol wind tunnel for aspiration efficiency, (3) to evaluate the sampler using model bioaerosols with a focus on the effects of sampling on microbial viability, and (4) to evaluate the sampler placed on the lapel of a mannequin at different wind directions in a wind tunnel. Relevance: This research will lead to the development of a unique, highly efficient personal bioaerosol sampler capable of collecting the inhalable participate mass and retaining microbial viability. The new device will not only be beneficial in occupational settings, but may also have future potential in high risk areas such as those following any possible biological attack.